1. Field of the Invention
This invention generally relates to digital electronics and more particularly to methods and associated circuits for detecting bit patterns.
2. Description of the Related Art
A bit stream consists of serially transmitted digital data bits. A specific sequence of bits, also known as a bit pattern, has special significance in some bit streams. For example, a bit pattern xe2x80x9c10101010xe2x80x9d can indicate that the next following bits in the bit stream constitute a distinct block of information.
Detecting bit patterns in a high-speed bit stream is specially challenging because pattern detection needs to be performed while the bit stream passes at a high rate. Thus, the pattern detector must be fast enough to keep up with the high speed bit stream, which can have rates of 1 Gbit/s (1 Giga bit per second) and higher.
From the foregoing, a method and associated circuits for detecting bit patterns in a high-speed bit stream is highly desirable.
A first single-bit detector reads a first bit of a serial bit stream and compares it to a first bit of a pattern. If the first bit of the bit stream and the first bit of the pattern have the same logical value, a second single-bit detector is enabled to read a second bit of the bit stream. The second single-bit detector then reads the second bit of the bit stream and compares it to a second bit of the pattern. N single-bit detectors are employed to detect an N-bit pattern. The aforementioned reading and comparison actions continue until all bits of the pattern are detected. By performing the comparison as each bit of the bit stream arrives at a node, the present single-bit detectors can be used in a pattern detector to detect bit patterns in high-speed bit streams.
In one embodiment, the first single bit detector and the second single bit detector are synchronized using different portions of a clock signal to lower the clock frequency requirement of the pattern detector.
These and other features of the present invention will be apparent to a person of ordinary skill in the art upon reading the following description and figures.